Golf club head



4 Claims. (Cl. 2734-174) 'This invention relates to golf club heads randmore particularly to wooden golf heads impregnated with Vinyl resins forrendering the headjresistant orn immune to the efects of moisture suchlas swelling, deformation, and eventual deterioration, otherwise toimprove its physical character, to change its physical properties, totoughen it, and generally giving itthose characteristics which it isdesired tohave imparted thereto.

This `application isl a ldivision of, my copending appli- `cation SerialNo. 703,343, tiled December 17, l1957 and since matured into PatentNo:2,936,248.

Heretofore heads have been impregnated with matelrials but they did nothavefa low' moisture transmission and did not prevent swelling. lAlso amethod has been employed in which a `iluid .pelymerizablelnon-stabilizfed resin or monomer is 'fused in sucha'manner as to allowthe monomer to polymerize after it has, penetrated into the wood, withthe attendant diiiiculty of controlling'polymerization. f' e A Thismethod has resulted `in a majrdrawback, namely resin exudation, 4whichmay occur subsequent` to penetration and after the heads have beenremoved from the impregnating bath to be) dried, with undesirablesurface tackiness accompanying` suchuexudation. This has been a problemof longstanding which heretofore required special and expensivefinishing treatment steps.

It is among the objects of, this invention to provide an impregnatedgolf "head having improved properties and characteristics"involvingauniform deep penetration into the head as well as optimum andlasting moisture-resistant resin impregnation of the article without theaccompanying exdation and `surface tackiness heretoiore experienced.v pY i This is accomplished byV employing `an impregnating resin in theform of `a `vinylpolymer-or copolymer thereof in Aa mixture of solventsof the class of ketones and of the class of aromatic hydrocarbons,preferably such solvents having differentV vapor pressures and differentevaporation rates at room temperature so as to provide an impregnatingsolution of low viscosity and high penetrating power and by subsequentlycontrolling the rate of evaporation of the solvents iiromthe club headin a manner to discourage and avoid resin exudation. W Y

According to one method employed for impregnating the heads of thepresent invention, the heads are immersed in a bath oftheimpregnatingsolution at atmosphericpressureior a-predetermined length oftime sucient to permit the desired penetration, after which the. headsare removed and subjected Ato a partial drying at room temperatureduring which time the ketone solvent evaporates morefrapidly than thearomatic hydrocarbon solvent from the surface of the head and, ineffec-t, builds up a resin barrier which prevents exudation of the resint when the heads are thereafter subjected to a drying period at a hightemperature-to complete the evaporation of the solvents therefrom. n A uK v Another method of forming the heads of the present invention is tosubject 'the heads to vacuum until a,

Inited States Patent() 3,002,757 Patented Get. 3, 1961 stable conditionis achieved and thereafter impregnating the head at high pressure withthe impregnating solution. This procedure greatly shortens the time fortreating the head and'permits a higher solid content of the solution tobe used and still `achieve the desired penetration. Thereafter the headis removed and partially dried at room temperature land then completelydried at an elevated tempera-ture as before.

By so impregnating the head I am able to control the weight of the headso as to eliminate unneocessary coring in order to insert weights as hasbeen the prior practice; I iam able to produce amore stable head in thatthe iibers in the head are adequately coated with the resin; an improvedtoughness of the material of the head `is achieved, all with the addedresult that the head has a low moisture transmission and is moreresistant to taking on moisture and swelling in use.

Other features and advantages will be apparent from the specificationand claims when considered in connection with the dravlngs in which:

FIGURE lis a side View, partly in section, of a wooden golf club head.

FIG. 2 isa view,'partly in elevation, taken on line 2-2 of FIG. 4l.

FIG. 3 is a sectional view taken on line '3-3 of FIG. l. A

The golf club4 head 10 is made of wood, preferably persimmon, and isshaped to the required shape. It is then impregnated with animpregnating solution comprising a polymerized resin and a mixture ofsolvents of the class of ketones and ofthe class of aromatichydrocarbons, which solution has a low viscosity and high penetratingpower so that the impregnation will extend into the head a substantialdistance from all faces thereof as indicated by heavy shading in thesectional views or the drawings. lAfter the solvents have been removed,there will be incorporated in the head the polymerized resin so that thehead has a low moisture transmission copolymers thereof such `aspolyvinyl chloride and 'copoly- Amers ythereof'may be used. These resinsare such that when impregnated into the body of the head they tend tocoat the wood fibers and to toughen the head. Also,

heads impregnated with polyvinylidene chloride particularly have a lowmoisture transmission and substantially resist the passage of moistureinto the head and the wood fibers thereof` so as to prevent undesirableswelling of the head. The resin soincorporated in the head tends also toadd weight to the head in desired amounts to control the weight of thehead as required. With the heads of the present invention coringthereof, as now employed for the insertion of the usual weights in thehead, is eliminated or greatly reduced.

TheV ketones `usedin the solution are those whichfdissolve the resin,reduce the viscosity of the solutiomsw'ell the wood to permit betterpenetration of the solution and have .a high evaporation rate. Whilediethyl ketone, methyl ethyl ketone, methyl isobutyl ketone and the likemay be used, it is at present preferred to use acetone.

'The aromatichydrocarbons used in the solution are those whichhave somesolvent effect on the resin, cause the" solution to have a greaterpenetration into the wood and act to stabilize the solution. Also theyare the "ones whichcanbe readily evaporated fromn the head, althoughencarar they have a lower evaporation rate than the ketonesl pressure, a12% solution has been found to be highly satisfactory. This, of course,can vary slightly in either direction depending upon the density andnature of the wood of the head. When pressure impregnation is employedwherein the solution is forced into the pores of the head undersubstantial pressure, solutions of between 24 to 27% have been foundmost satisfactory. However, here again this percentage may vary slightlyabove and below these Values depending upon the nature of the head,`

i.e., the density of the wood and other characteristics affecting thepenetration of the resin.

l It will be noted from the shading in the drawings that theimpregnating resins extend a substantial distance in from each surfaceof the head. With this depth of penetration, the grooves 11, 12 for theusual face plate 13 and sole plate 14 in the face 15 and bottom surface1.6 can be safely cut since there is substantial resin content inwardlyof these cuts so that passage of moisture into the head through the cutsis effectively prevented. Further the face plate can be cemented inposition by means of an epoxy resin which not only adheres the faceplate, which may be of plastic, fiber or the like material, to the headbut also aids in sealing the cut and preventing moisture from passinginto the head. Similarly, the sole plates can and 2 so that the passageof moisture along the screws r Y and into the head is substantiallyeliminated.

It will be seen, therefore, that I have provided a novel golf head ofthe wood type which is impregnated with a polymerized resin, preferablypolyvinylidene chloride, to

evaporated slowly from the surface of the heads and the resin thereinwill set up a barrier to the exudation of the resin from the head as theremainder of the solvent is driven off from the head. Highertemperatures at this time would build up vapor pressures in the head anddrive out the resin. The heads are thereafter finish-dried in a heatingchamber or hot room having a good circulation of air therein and beingat a temperature of approximately 150 F. for 24 hours or 125 F: for 40hours, after which the heads are removed and processed into golf clubs.V

' If the heads are to be pressure impregnated they are inserted in avessel and vacuum of up to 25 inches of mercury applied to the vesseland the vacuum is maintained on the vessel fora period of 10-30 minutesor until the reading becomes stable indicating a complete evacuation ofthe heads. The vacuum-is shutolf and the impregnating solution is placedin the vessel under a minimum of 90 pounds p.s.i. pressure. Since theimpregnating material is ,being forced into the heads under pressure, itcan have a higher solid content. `At present, it is preferred to have asolid content of 24%. The heads are left under pressure for 24 hours andare then removed and air dried at room temperature for from 4-12 hours.Thereafter they are dried in the hot room at a temperature of 150 F. for24 hours. f

The feature of applicants novel methods-resides in the fact that a deeppenetration is obtained and that the heads are partially dried at roomvtemperature after they are taken from the solution which sets up abarrier in the surface of the heads which prevents exudation of theresin while permitting the solvents to be removed at the hightemperature, thus producing an improved head.

Variations and modifications may be made within the scopel of the claimsand portions of the improvements may be used without others. Y

I claim:

1. AV golf club head comprising a wooden head im pregnated with aself-sealing residue, after evaporation,

an extent which effectively prevents the swelling of the head and whichresin coats the fibers of the head to, in effect, seal them frommoisture, and which is provided with a smooth outer surface since theimpregnation of the head by my novel method prevents exudation of theresin from the head during drying thereof.

The head of the present invention can be produced by impregnation atatmospheric pressure or by a pressure impregnation process. Each ofthese processes will be described and in order to clearly understand theprocesses specitic values utilized in each are being given by way ofexample.

In the process wherein the heads are impregnated at atmosphericpressure, the heads are permitted to stand and are air dried for aperiod of at least a week. They are then immer ed in a tank ofimpregnating solution for a period of approximately 66 hours. Thesolution comprises a resin, preferably a polyvinylidene resin (Geon 222)dissolved in a solvent comprising half acetone and half toluene. Thesolution has a 12% solid content. Such a solution can be produced from 5gallons acetone, 5 gallons toluene and 9.45 pounds of resin, whichsolution is vigorously agitated during the mixing thereof. The viscosityof the solution at 75 F. or room temperature is 19-20 seconds asdetermined by a Zahn No. 2 cup and the specific gravity is .881.

After the heads have been immersed for 66 hours they vare removed fromthe solution and are partially dried at room temperature of between 60100 F. for from 4 to l2 hours aud preferably for 12 hours at 75 F. Ihave found that this is an important step in preventing exudation fromthe heads. A possible explanation of this discovery is that acetonewhich has a relatively high evaporation rate, it being about 5-1 withrespect to toluene, is

of a deep penetrating solution comprising a vinyl resin, a solventhaving a low evaporation rate and a solvent having a higher evaporationrate, said head being tough, having a high resistance to moisturetransmission whereby swelling of the head therebyis resisted and beingfree of tackiness caused by resin exudation therefrom.

2. A golf club head comprising a wooden head impregnated with aself-sealing residue, after evaporation,

of a deep penetrating solution comprising polyvinylidene chloride, aketone having a low evaporation rate and an aromatic hydrocarbon havinga higher evaporation rate than the ketone, said head being tough, havinga high resistance to moisture transmission whereby swelling of the headthereby is resisted and being free of tackiness head being tough, havinga high resistance to moisture transmission whereby swelling of the headthereby is resisted and being free of tackiness caused by resinexudation therefrom.

4. A golf club head comprising a Wooden head impregnated with aself-sealing residue, after evaporation, of a deep penetrating solutioncomprising polyvinylidene chloride, acetone having a low evaporationrate and toluene having a higher evaporation rate than the acetone, saidhead being tough, having a high resistance to moisture transmissionwhereby swelling of the head thereby is resisted and being free oftackiness caused by resin exudation therefrom, a sole plate for thehead, and means for securing the sole plate to the head including screwscoated with epoxy resin and extending into the head.

(References on following page) References Cited in the le of this patentUNITED STATES PATENTS Rose June 15, 1926 Booty et al Dec. 20, 1938Arnold etal Nov. 16, 1943 Cheyney Jan. 15, 1946 Wiles Nov. 7, 1950 6Aust-in Apr. 8, 1952 Greenlee Nov. 16, 1954 OTHER REFERENCES Industrialand Engineering Chemistry for March 1942, pages 327-332 cited.

Industrial and Engineering Chemistry for April 1943, pages 422428 cited.

1. A GOLF CLUB HEAD COMPRISING A WOODEN HEAD IMPREGNATED WITH ASELF-SEALING RESIDUE, AFTER EVAPORATION, OF A DEEP PENETRATING SOLUTIONCOMPRISING A VINYL RESIN, A SOLVENT HAVING A LOW EVAPORATION RATE AND ASOLVENT HAVING A HIGHER EVAPORATION RATE, SAID HEAD BEING TOUGH, HAVINGA HIGH RESISTANCE TO MOISTURE TRANSMISSION WHEREBY SWELLING OF THE HEADTHEREBY IS RESISTED AND BEING FREE OF TACKINESS CAUSED BY RESINEXUDATION THEREFROM.